Field of the Invention
The present invention relates to a head and neck simulation phantom device, and more particularly, to a head and neck simulation phantom device that is capable of measuring radiation, instead of the human body, and evaluating dose errors generated from teeth and implants within the body.
The present invention further relates to a head and neck simulation phantom device and that is capable of selectively disposing teeth and implants to express the real state of a patient's teeth, so that artifacts appearing on computed tomography CT images by the teeth and implants are obtained, thereby conducting dose verification on the corresponding regions of the CT images at which the artifacts appear.
Background of the Related Art
Head and neck cancers contain various kinds of cancers such as laryngeal cancer, oral cancer, nasal cavity cancer, pharyngeal cancer and so on, and since their ranges for treatment are relatively large and their shapes are irregular, radiation treatment is frequently and usefully applied to them. According to the biological characteristics of the head and neck cancers and the development of radiation treatment technologies, clinical treatment effects are gradually increased, and the exposure dose to salivary glands and eyeballs as main protection organs becomes minimized, thereby making it possible to conduct radiation treatment more accurately and effectively.
So as to predict the absorbed dose to the patient upon the radiation treatment of his or her head and neck cancer, CT images are photographed before the radiation treatment, and the absorbed dose is predicted from the CT images by using information (for example, Hounsfield Unit HU and electron density), and after the predicted absorbed dose is optimized, the radiation treatment starts. Accordingly, the qualities of CT images should be excellent because the cancer to which the dose is transmitted and the protection organs on which the transmitted dose has to be minimized are defined more accurately on the basis of the CT images, and further, the electron density of the treatment region is obtained from the CT images, thereby conducting the dose calculation more accurately. So as to conduct the radiation treatment more accurately and safely, above all, it is very important to acquire the CT images having excellent qualities and accurate information.
By the way, if the CT photographing for the head and neck cancer patient is conducted for his or her radiation treatment in the state where he or she wears dental prosthesis like implants, higher atomic number materials than HU 2000, like titanium used as the materials of the implants, are contained in the reconstruction of the CT images, so that they appear on the CT images, as artifacts which do not exist really around the implants but look like they exist on the CT images. Therefore, different values from the inherent HU values of the real treatment region are expressed on the CT images. Such artifacts appearing on the CT images cause the qualities of images to be deteriorated, and further, the information required for dose calculation is not accurately obtained from the CT images, thereby increasing predicted dose errors.
So as to enhance the accuracy in prediction of the dose on the CT images upon radiation treatment planning, accordingly, the CT images on which the artifacts are corrected are required. As a result, algorithms for restoring or correcting the image information damaged by the artifacts have been applied in a variety of ways, and further, many studies on the reconstruction of CT images with improved quality have been proposed wherein the CT photographing is used together with megavoltage CT or PET on which artifacts generated from high atomic number metal materials are relatively small. However, even if the qualities of gross and quantitative images are improved through the post process on the images, it should be verified whether how much the dose prediction is accurate so as to trust the image information restored from the points at which the artifacts are produced. Accordingly, the accurate prediction in the quantity of absorbed dose to be transmitted to the patient is more specified and quantified, and through the accurate prediction, there is a need to select effective artifact reducing algorithm.
Generally, the head and neck are representative regions on which artifacts are typically produced upon the reconstruction of CT images due to the use of the patient's dental prosthesis like implants. Further, the component ratios of non-uniform materials like mouth and mandible are high so that there is a high probability of the generation of dose errors. Therefore, there is a need for evaluating the accuracy in the prediction of the absorbed dose of the teeth and implants on the CT images upon the radiation treatment, while the teeth and implants are simulating the patient's head and neck region and mouth structure and the dose verification for them is being conducted. Further, there is a need for a head and neck simulation phantom device that is capable of selectively disposing the teeth and implants to express the real state of the patient's teeth, so that artifacts appearing on the CT images by the teeth and implants are accurately obtained, thereby conducting dose verification on the corresponding regions of the CT images at which the artifacts appear.